Optical storage system having optical head with a solid immersion lens and operating on media with at least two recording layers

Abstract

A system for reading or writing data from or to a bilevel optical recording medium with a flying head. The system includes a head having a slider and a solid immersion lens mounted at least partially within the slider. The solid immersion lens has a partial spherical surface and a substantially flat surface. The head also has an objective lens mounted to the slider. The system also includes a multilevel recording medium. The medium has a first media layer and a first substrate layer adjacent to the first media layer. The medium also has at least one second media layer adjacent the side of the first substrate layer opposite from the first media layer, and a second substrate layer adjacent the side of the second media layer opposite from the first substrate layer. The total effective numerical aperture of the system is greater than one for all layers.

What is claimed is: 
     
       1. A data storage system for using radiation energy to read or write data from or to an optical recording medium having at least two recording layers spaced from each other by less than one wavelength of the radiation energy, comprising: an optical imaging module configured to have a combination lens and to have an adjustable focus; and   an optical head disposed relative to said optical imaging module and configured to have (1) a slider, (2) a solid immersion lens fixed to said slider and having a partial spherical surface and a substantially flat surface, and (3) an objective lens fixed to said slider to be spaced by a predetermined distance relative to said solid immersion lens,   wherein said imaging optical module and said optical head are operable to focus the radiation energy to at least two different positions spaced away from said flat surface of said solid immersion lens by two different distances that are less than one wavelength of the radiation energy by adjusting the focus of said optical imaging module for reading and writing information in at least two different recording layers in an optical recording medium.   
     
     
       2. The system of claim 1, wherein said optical imaging module includes a relay lens and an imaging lens that are positioned relative to each other to produce said adjustable focus by moving said relay lens with respect to said imaging lens. 
     
     
       3. The system of claim 2, wherein said relay lens is adjusted to shift the focus position of the radiation energy by an amount up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       4. The system of claim 1, wherein said slider includes an air-bearing surface, and said flat portion of said solid immersion lens is substantially co-planar with said air-bearing surface. 
     
     
       5. The system of claim 1, wherein said solid immersion lens has a shape of a hemisphere. 
     
     
       6. The system of claim 1, further comprising an optical recording medium which comprises: a first media layer;   a first substrate layer adjacent to said first media layer and less than one wavelength thick;   a second media layer adjacent the side of said first substrate layer opposite from said first media layer; and   a second substrate layer adjacent the side of said second media layer opposite from said first substrate layer,   where said optical recording medium is positioned relative to the optical head in such a way that said first media layer is less than one wavelength away from said flat surface of said solid immersion lens and a total effective numerical aperture of the system is greater than one for all layers.   
     
     
       7. The system of claim 6, wherein said first substrate layer having a thickness of up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       8. The system of claim 6, wherein the total thickness from a bottom of said partial spherical surface of said solid immersion lens to said second media layer is up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       9. The system of claim 6, wherein on the side of said first media layer opposite said first substrate layer is located a transparent dielectric material. 
     
     
       10. The system of claim 9, wherein said transparent dielectric material includes silicon nitride. 
     
     
       11. The system of claim 6, wherein said second substrate is made of a material selected from a group consisting of plastic, glass, or aluminum. 
     
     
       12. The system of claim 6, wherein one of said first or second media layers is of a phase-change type or of a magneto-optic type. 
     
     
       13. The system of claim 6, wherein said second media layer includes a selectively reflective material. 
     
     
       14. The system of claim 6, wherein said first and second media layers are spaced from each other less than the optical tolerance range of said solid immersion lens. 
     
     
       15. A method for using radiation energy to read or write data from or to an optical recording medium having at least two recording layers spaced from each other by less than one wavelength of the radiation energy, comprising: coupling radiation energy to and from the recording layers by using an optical head which includes (1) a slider, (2) a solid immersion lens fixed to said slider and having a partial spherical surface and a substantially flat surface, and (3) an objective lens fixed to said slider to be spaced by a predetermined distance relative to said solid immersion lens; and   disposing an optical imaging module relative to said optical head to couple radiation energy to said optical head, said optical head configured to have a combination lens that has an adjustable focus,   wherein said imaging optical module and said optical head are operable to focus the radiation energy to at least two different positions spaced away from said flat surface of said solid immersion lens by two different distances that are less than one wavelength of the radiation energy by adjusting focus of said optical imaging module for reading and writing information in at least two different recording layers in an optical recording medium.   
     
     
       16. A data storage system for using radiation energy to read or write data from or to an optical recording medium having at least two recording layers spaced from each other less than one wavelength of the radiation energy, comprising: a movable relay lens;   an imaging lens disposed relative to said relay lens; and   an optical head disposed relative to said relay lens and said imaging lens, comprising: (1) a slider; (2) a solid immersion lens fixed to said slider and configured to have a partial spherical surface and a substantially flat surface; and (3) an objective lens fixed to said slider to be spaced by a predetermined distance relative to said solid immersion lens,   wherein said relay lens, said imaging lens and said optical head are operable to focus the radiation energy to at least two different positions spaced away from said flat surface of said solid immersion lens by two different distances that are less than one wavelength of the radiation energy by varying a position of said relay lens for reading and writing information in at least two different recording layers in an optical recording medium.   
     
     
       17. The system of claim 16, wherein said relay lens is adjusted to shift the focus position of the radiation energy by an amount up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       18. The system of claim 16, wherein said slider includes an air-bearing surface, and said flat portion of said solid immersion lens is substantially co-planar with said air-bearing surface. 
     
     
       19. The system of claim 16, wherein said solid immersion lens has a shape of a hemisphere. 
     
     
       20. The system of claim 16, wherein said objective lens is configured to have a numerical aperture of between about 0.45 and 1.0. 
     
     
       21. The system of claim 16, wherein said solid immersion lens is configured to have an index of refraction of between 1.4 and 2.5. 
     
     
       22. The system of claim 16, wherein the mass of said objective lens is less than about 35 milligrams. 
     
     
       23. The system of claim 16, wherein the radius of said spherical portion of said solid immersion lens is less than about 2 millimeters. 
     
     
       24. The system of claim 16, further comprising an optical recording medium which comprises: a first media layer;   a first substrate layer adjacent to said first media layer and less than one wavelength thick;   a second media layer adjacent the side of said first substrate layer opposite from said first media layer; and   a second substrate layer adjacent the side of said second media layer opposite from said first substrate layer,   where said optical recording medium is positioned relative to the optical head in such a way that said first media layer is less than one wavelength away from said flat surface of said solid immersion lens and a total effective numerical aperture of the system is greater than one for all layers.   
     
     
       25. The system of claim 24, wherein said first substrate layer having a thickness of up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       26. The system of claim 24, wherein the total thickness from a bottom of said partial spherical surface of said solid immersion lens to said second media layer is up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       27. The system of claim 24, wherein on the side of said first media layer opposite said first substrate layer is located a transparent dielectric material. 
     
     
       28. The system of claim 27, wherein said transparent dielectric material includes silicon nitride. 
     
     
       29. The system of claim 24, wherein said second substrate is made of a material selected from a group consisting of plastic, glass, or aluminum. 
     
     
       30. The system of claim 24, wherein one of said first or second media layers is of a phase-change type or of a magneto-optic type. 
     
     
       31. The system of claim 24, wherein said second media layer includes a selectively reflective material. 
     
     
       32. The system of claim 24, wherein said first and second media layers are spaced from each other less than the optical tolerance range of said solid immersion lens. 
     
     
       33. A method for using radiation energy to read or write data from or to an optical recording medium having at least two recording layers, comprising: providing an optical head which has a slider body, a solid immersion lens having a partial spherical surface and a substantially flat surface, and an objective lens, wherein said solid immersion lens and said objective lens are fixed to said slider to be spaced by a predetermined distance with respect to each other;   disposing a relay lens and an imaging lens relative to each other to couple radiation energy to an optical head;   placing th e optical recording medium relative to the optical head in such a position that the two recording layers are spaced from the flat surface by less than one wavelength of the radiation energy to form a near-field optical configuration; and   adjusting a position of said relay lens relative to said imaging lens to shift focussing position of the radiation energy between the at least two recording layers to retrieve or record information from and to the at least two recording layers,   wherein said relay lens, said imaging lens and said optical head in combination are operable to produce an effective total numerical aperture of greater than one for at least two recording layers.   
     
     
       34. The method of claim 33, further comprising: operating said solid immersion lens in a hemispherical regime with respect to the optical recording medium to optically address one recording layer; and   operating said solid immersion lens in a super-hemispherical regime with respect to the optical recording medium to optically address another recording layer.   
     
     
       35. The method of claim 33, further comprising: maintaining said solid immersion lens in either a super-hemispherical regime or a hemispherical regime with respect to the optical recording medium at all times for data readout or recording;   configuring the optical recording medium in such a way that the at least two recording layers are spaced from each other by less than the tolerance of the solid immersion lens; and   adjusting said relay lens to shift the focus of the radiation energy within the tolerance of the solid immersion lens.   
     
     
       36. The method of claim 33, wherein said relay lens is adjusted to shift the focus position of the radiation energy by an amount up to about r/n, where r is the radius of said partial spherical surface and n is the index of refraction of said solid immersion lens. 
     
     
       37. The method of claim 33, wherein said slider includes an air-bearing surface, and said flat portion of said solid immersion lens is substantially co-planar with said air-bearing surface. 
     
     
       38. The method of claim 33, wherein said solid immersion lens has a shape of a hemisphere. 
     
     
       39. The method of claim 33, wherein said objective lens is configured to have a numerical aperture of between about 0.45 and 1.0. 
     
     
       40. The method of claim 33, wherein said solid immersion lens is configured to have an index of refraction of between 1.4 and 2.5. 
     
     
       41. The method of claim 33, wherein the mass of said objective lens is less than about 35 milligrams. 
     
     
       42. The method of claim 33, wherein the radius of said spherical portion of said solid immersion lens is less than about 2 millimeters.